1. Field of the Invention
This invention relates to a picture processing apparatus for processing picture information introduced from a picture input unit such as an industrial camera by a raster scanning system.
2. Description of the Related Art
When one frame of a picture of a CRT display is introduced into a picture processing apparatus from a picture input unit (hereinafter referred to simply as a "camera") such as an industrial camera by a raster scanning system, the picture signal outputted by the camera comprises one vertical synchronizing signal VSYNC for establishing synchronization of a picture in the vertical direction, a plurality of horizontal synchronizing signals HSYNC for establishing synchronization of the picture in the horizontal direction, and a luminance signal PCSG which includes significant picture information. FIGS. 3(a) and (b) illustrate an example of a general picture signal waveform. FIG. 3(a) is a time chart of a signal waveform corresponding to one frame, and FIG. 3(b) is a time chart regarding one line in the horizontal direction.
The luminance signal PCSG is effective in a significant picture information interval PCPD, and the significant picture information interval PCPD is provided in sychronization with each horizontal signal HSYNC. In other words, the signficant picture information interval PCPD starts a predetermined period of time (the front porch time FP) after the horizontal synchronizing signal HSYNC is produced.
The front porch time FP from the horizontal synchronizing signal HSYNC to the start of the significant picture information interval PCPD generally differs from one type of camera to another. Since the conventional apparatus for introducing the picture is designed solely for a specific type of camera, the front porch time FP is set so as to conform to the picture signal from the camera. Accordingly, if a picture from the camera of a different type is to be introduced using the conventional picture introducing apparatus, the front porch time FP will not conform. As a result, the picture signal will not be introduced in a faithful and accurate manner.